Jordan Ellenberg devotes an installment of his Slate column to the question of whether 0.999... equals 1 and, if so, why.
Ellenberg cites the divisiveness of the question, provides historical context, and offers commentary on arbitrariness and definition in mathematics:
Just because we can assign whatever meaning we like to a string of mathematical symbols doesn’t mean we should. In math, as in life, there are good choices and there are bad ones. In the mathematical context, the good choices are the ones that settle unnecessary perplexities without creating new ones.